It had been 400 years since Alaska’s Mount Edgecumbe last erupted. The long-dormant volcano towers at the southern end of Kruzof Island. The 8,000-plus residents of Sitka delight in the mountain’s majestic snow peak, while simultaneously taking for granted that there is no imminent danger from the volcano that is a mere 15 miles (24 km) away. Their complacency was challenged the day they looked out and saw the tell-tale smoke of a pending eruption emerging from the supposedly-dormant volcano.

The date was April 1, 1974. An otherwise peaceful day was thrown into pandemonium when a black plume of smoke rose without warning from the volcano’s crater. Word spread rapidly throughout the coastal community. Many residents streamed from their homes, took one look at the ominous sight, and rushed back inside to hurriedly pack a few belongings in preparation for a hasty escape.

Breathless reports of an unexpected eruption made their way to Juneau, where orders were given, dispatching a Coast Guard helicopter to Mount Edgecumbe for closer inspection. As the pilot approached, his concern grew as the plume of smoke intensified. At last, as the smoke cleared enough for him to get a better view of the source of the smoke, the pilot’s worries were replaced with laughter. There, in the cone of the volcano, he saw a pile of burning tires. Next to the tires, spray-painted in the snow, in 50-foot high black letters, were the words, “APRIL FOOL.”

The “eruption” of Mount Edgecumbe was a prank three years in the making. Oliver “Porky” Bickar came up with the idea in 1971 and began collecting old tires. He accumulated 70 of them, keeping them in an airplane hanger. Bickar wanted to wait until the weather conditions were perfect. When he looked out his window on the morning of April 1, 1974, and he could see a clear view of Mount Edgecumbe, he knew it was the day to put his plan into motion.

Bickar secured a helicopter and the help of some friends to move the tires to the crater of the volcano. They also took along some smoke bombs and several gallons of kerosene. The pranksters had the foresight to let local law enforcement and air traffic control have advance knowledge of their plans. As they returned to Sitka, the controller said, “You have clearance. And by the way, the son-of-a-[gun] looks fantastic.”

Once word reached the residents of Sitka that the end of the world was not imminent, fear and anxiety melted into good humor. Six years later, when Mt. St. Helens erupted, an attorney in Denver, Colorado wrote to Bickar, saying, “This time… you’ve gone too far.”

Bickar was already known as a prankster before the Mount Edgecumbe incident. He once used a backhoe to drop an entire tree in the middle of a friend’s driveway. He also enjoyed putting plastic flamingoes in trees along the route of tour boats to confuse those who were looking for local wildlife.

Bickar died in 2003 at the age of 79. He continued to be a prankster until the end, but none of his jokes ever topped the great volcano eruption of Mount Edgecumbe.

Read about more practical jokes.

Read more fun facts about volcanoes.